George Buckbee is best known as the mouthpiece for Expertune, but he also is the president of a little known effort called PIDTutor.
In that persona, George has written and published a fine little book, almost a "chapbook" really, called Mastering Split-Range Control.
This little book is a "back to basics" approach to split range control. It assumes you know little or nothing about how to use two control valves to control one process variable.
In 30 pages, you will learn how split-range control works, get some troubleshooting guidance, and get a list of references.
Nice job, George!
Managing Split-Range Control is available from PIDTutor.